This invention relates to a sheet transfer apparatus for an image reading apparatus, which is used with an image forming apparatus such as a copier, facsimile, printer and scanner. The sheet transfer apparatus continuously draws or receives a series of sheets on a sheet supply tray, and aligns and stacks the sheets after images thereupon have been read.
Conventionally, a set of the sheets placed on the sheet supply tray is read sequentially, and is discharged to a discharge tray. When the sheets stacked on the discharge tray, or the sheets after being read on both sides, are required to be reorganized into their original order, a switchback path disposed in the sheet transfer apparatus reverses the sheet from front to back thereof.
Examples of the sheet transfer apparatus having such a switchback path are disclosed in Japanese Patent Publication (KOKAI) No. 09-292742 and Japanese Patent Publication (KOKAI) No. 05-30724.
An automatic document feeder apparatus disclosed in Japanese Patent Publication No. 09-292742 sequentially draws the sheets stacked on the sheet supply tray, transfers the sheets to a platen glass by a transfer belt, and sets the sheets on the platen glass to read images on the sheets. The apparatus is structured to reverse and transfer the sheets via the switchback path to organize the page order of the sheets. The switchback path is formed between the transfer belt and the discharge tray.
The sheet transfer apparatus disclosed in Japanese Patent Publication No. 05-30724 is structured to arrange the switchback path below the sheet supply tray. Vertical positions of the sheet supply tray and discharge tray are reversed from those in Japanese Patent Publication No. 09-292742.
However, in the switchback path for reversing the sheet from a front side to a back side, paper jam occurs easily, because the sheet is forced to bend and is subjected to back and forth movement in a narrow path. However, in the sheet transfer apparatus relating to the aforementioned prior art, there has been no consideration regarding measures of recovering from the paper jam that occurs in the switchback path between the transfer belt and the discharge tray.
Measures to remove such paper jam include opening the switchback transfer path with one edge of a guide portion of the switchback transfer path as a pivot. However, enough opening angle is not available because a sheet supply tray or the like is disposed at an upper portion.
This type of sheet transfer apparatus is capable of handling sheet sizes up to A3 or B4. However, since the most commonly used sheet size is A4, it is possible to deal with the paper jam by opening a sheet transfer inlet of the switchback path, if the switchback path is designed to be capable of being opened.
For this reason, it is proposed that only a sheet transfer inlet of the switchback path corresponding to the A4 size is designed to be capable of being opened. However, since the larger size sheet such as A3 or B4 size uses far deeper areas of the switchback path, the entire switchback path is required to be opened to handle the paper jam.
An object of the present invention is to provide the sheet transfer apparatus that makes it extremely easy to handle the sheet jam at the sheet transfer inlet of the switchback path where the sheet jam occurs relatively easily, and even if the sheet jam occurs at a deeper area, an operator can handle the sheet jam easily.
Further objects and advantages of the invention will be apparent from the following description of the invention.
The first aspect of the present invention provides a sheet transfer apparatus including sheet supply means for drawing out a sheet on a sheet supply tray; transfer means for receiving the sheet from the sheet supply means and for placing it at a predetermined location on a platen of an image reading apparatus; discharge means for receiving the sheet after images thereon being read on the platen and for discharging it to a discharge tray arranged below the sheet supply tray; and a switchback path disposed inside the discharge tray for reversing the sheet as needed after reading images thereon. The switchback path is structured to have the first opening portion for opening a sheet inlet of the switchback path, which is a part of the discharge tray, and the second opening portion adjacent to the first opening portion.
Here, the first and second opening portions are connected to an apparatus frame such that they can rotate around shafts. One end of the second opening portion is connected to an apparatus frame such that the second opening portion can rotate around the shaft. The other end of the second opening portion hinged to the first opening portion. Furthermore, an opening angle of the first opening portion is configured to be larger than that of the second opening portion.
This configuration makes it easier to handle paper jam that occurs at the sheet inlet of the switchback path, and also makes it easier to handle the paper jam farther from the sheet inlet when necessary.
Further, in the sheet transfer apparatus, the first opening portion and the second opening portion are provided with opening locking means for controlling the opening operation so that the opening portions will not open inadvertently in a normal state.
The second aspect of the present invention provides a sheet transfer apparatus including sheet supply means for drawing out sheets on the sheet supply tray; transfer means for receiving the sheet from the sheet supply means and for placing it at a predetermined location on the platen of the image reading apparatus; discharge means for receiving the sheet after images thereon being read on the platen and for discharging it to the discharge tray arranged below the sheet supply tray; and the switchback path disposed inside the sheet supply tray for reversing the sheet as needed after reading images thereupon. The switchback path is structured to have a first opening portion for opening a sheet inlet of the switchback path, which is a part of the sheet supply tray, and a second opening portion adjacent to the first opening portion.
Here, in the first opening portion, an end portion of the switchback path is supported on a shaft such that the first opening portion can rotate around the shaft.